The present invention relates generally to handheld power tools, and specifically to combustion-powered fastener-driving tools, also referred to as combustion tools.
Combustion-powered tools are known in the art, and one type of such tools, also known as IMPULSE® brand tools for use in driving fasteners into workpieces, is described in commonly assigned patents to Nikolich U.S. Pat. Re. No. 32,452, and U.S. Pat. Nos. 4,522,162; 4,483,473; 4,483,474; 4,403,722; 5,197,646; 5,263,439 and 6,145,724, all of which are incorporated by reference herein. Similar combustion-powered nail and staple driving tools are available commercially from ITW-Paslode of Vernon Hills, Ill. under the IMPULSE®, BUILDEX® and PASLODE® brands.
Such tools incorporate a generally pistol-shaped tool housing enclosing a small internal combustion engine. The engine is powered by a canister of pressurized fuel gas, also called a fuel cell. A battery-powered electronic power distribution unit produces a spark for ignition, and a fan located in a combustion chamber provides for both an efficient combustion within the chamber, while facilitating processes ancillary to the combustion operation of the device. The engine includes a reciprocating piston with an elongated, rigid driver blade disposed within a single cylinder body.
Upon the pulling of a trigger switch, which causes the spark to ignite a charge of gas in the combustion chamber of the engine, the combined piston and driver blade is forced downward to impact a positioned fastener and drive it into the workpiece. The piston then returns to its original, or pre-firing position, through differential gas pressures within the cylinder. Fasteners are fed magazine-style into the nosepiece, where they are held in a properly positioned orientation for receiving the impact of the driver blade.
Conventional combustion fastener driving tools employ two types of fuel delivery systems, mechanical fuel injection and electronic fuel injection. With mechanical fuel injection, the fuel cell is provided with a metering valve, either affixed to the fuel cell or to the tool. The fuel cell is inserted into a fuel cell chamber of the fuel cell with the bottom of the fuel cell facing generally towards the workpiece when the tool is oriented operationally. Once a fuel cell door is closed, formations on the door and/or internal linkages cause the fuel metering valve to dispense a measured quantity of fuel to the tool's combustion chamber.
When electronic fuel injection is employed, the delivery of fuel is controlled by a central processing unit (CPU) typically incorporating a microprocessor. In such configurations, the fuel cell is inserted into the fuel cell chamber in the opposite orientation relative to the mechanical fuel injection configuration. As such, the fuel cell is inserted with the dispensing end toward the tool's nosepiece. Once inserted, the fuel cell stem is sealingly engaged or coupled to a fuel injector controlled by the CPU.
Manufacturers have been forced to provide separate tool housings for each of the above-identified fuel delivery configurations. Such separate configurations entail separate fuel cell access doors, among other things.
In addition, in instances when electronic fuel injection is selected, a fuel line is used to transmit the fuel from the injector to the combustion chamber. Due to the cramped environment of the tool housing, it has been found that conventional fuel fittings for sealingly transmitting the fuel take up needed space, and often impair fuel flow.
Thus, there is a need for a combustion-powered fastener-driving tool which addresses the problem of multiple housings for various fuel delivery options. There is also a need for such a tool with a fuel line configured for providing sealed connections without unnecessarily impeding fuel flow.